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Taking photos of Slides
Taking good quality images of your fluorescent fibre slides - against the right background - takes a little bit of set up.
You will need:
- A mid-range camera (18+ megapixel, minimal lens distortion, works well in low light)
- A tripod
- A printer (for printing the slide background)
- Fibre slides mounted on a transparent material (e.g. acetate)
- An ultraviolet torch
Print off fibre-background.pdf. This will be the background of your slide, and works well with slides ~12cm x 5cm.
- Set up the camera on the tripod, so that all four corner markers on
fibre-background.pdfare completely in frame.
- Place your slide so that all fibres are inside the central black rectangle. This is the only place the model will look at; all fibres outside of this will be missed in the count. Make sure that there is nothing covering the four corner markers. If there is, preprocessing will fail for that image.
- Illuminate the slide with a UV torch & take the image (after focussing as best you can)
- Use manual focus exclusively. Adjust it while looking at a zoomed in image if possible, to ensure sharpness.
- Use a remote trigger or self-timer to make sure your hand is not on the camera when it starts taking images. Jogging the camera while depressing the button is a common cause of unusable images.
- Favour low ISO and slow shutter speed - to give enough light without causing graininess in the image.
- Take raw format images - lossy compression (e.g. JPEGs) can produce artefacts that affect pre-processing and the eventual count